As above reported, the K116W variant DT388-IL-3 molecule (DT388-IL-3[K116W] or SL-501) displayed greater IL-3R binding affinity and cytotoxic activity against AML blasts than SL-401 and possesses low activity against normal hematopoietic progenitor/stem cells [82,83]. Here, IL3RA is linked to acute myeloid leukemia.